Overview

A seizure is a sudden, uncontrolled electrical disturbance in the brain. It can cause changes in your behavior, movements or feelings, and in levels of consciousness. If you have two or more seizures or a tendency to have recurrent seizures, you have epilepsy.

There are many types of seizures, which range in severity. Seizure types vary by where and how they begin in the brain. Most seizures last from 30 seconds to two minutes. A seizure that lasts longer than five minutes is a medical emergency.

Seizures are more common than you might think. Seizures can happen after a stroke, a closed head injury, an infection such as meningitis or another illness. Many times, though, the cause of a seizure is unknown.

Most seizure disorders can be controlled with medication, but management of seizures can still have a significant impact on your daily life. The good news is you can work with your health care professional to balance seizure control and medication side effects.

Symptoms

With a seizure, signs and symptoms can range from mild to severe and vary depending on the type of seizure. Seizure signs and symptoms may include:

Temporary confusion

A staring spell

Uncontrollable jerking movements of the arms and legs

Loss of consciousness or awareness

Cognitive or emotional symptoms, such as fear, anxiety or deja vu

Doctors generally classify seizures as either focal or generalized, based on how and where abnormal brain activity begins. Seizures may also be classified as unknown onset, if how the seizure began isn't known.

Focal seizures

Focal seizures result from abnormal electrical activity in one area of your brain. Focal seizures can occur with or without loss of consciousness:

Focal seizures with impaired awareness. These seizures involve a change or loss of consciousness or awareness. You may stare into space and not respond normally to your environment or perform repetitive movements, such as hand rubbing, chewing, swallowing or walking in circles.

Focal seizures without loss of consciousness. These seizures may alter emotions or change the way things look, smell, feel, taste or sound, but you don't lose consciousness. These seizures may also result in the involuntary jerking of a body part, such as an arm or leg, and spontaneous sensory symptoms such as tingling, dizziness and flashing lights.

Symptoms of focal seizures may be confused with other neurological disorders, such as migraine, narcolepsy or mental illness.

Generalized seizures

Seizures that appear to involve all areas of the brain are called generalized seizures. Different types of generalized seizures include:

Absence seizures. Absence seizures, previously known as petit mal seizures, often occur in children and are characterized by staring into space or by subtle body movements, such as eye blinking or lip smacking. These seizures may occur in clusters and cause a brief loss of awareness.

Tonic seizures. Tonic seizures cause stiffening of your muscles. These seizures usually affect muscles in your back, arms and legs and may cause you to fall to the ground.

Atonic seizures. Atonic seizures, also known as drop seizures, cause a loss of muscle control, which may cause you to suddenly collapse or fall down.

Clonic seizures. Clonic seizures are associated with repeated or rhythmic, jerking muscle movements. These seizures usually affect the neck, face and arms.

Tonic-clonic seizures. Tonic-clonic seizures, previously known as grand mal seizures, are the most dramatic type of epileptic seizure and can cause an abrupt loss of consciousness, body stiffening and shaking, and sometimes loss of bladder control or biting your tongue.

Causes

Nerve cells (neurons) in the brain create, send and receive electrical impulses, which allow the brain's nerve cells to communicate. Anything that disrupts these communication pathways can lead to a seizure.

The most common cause of seizures is epilepsy. But not every person who has a seizure has epilepsy. Sometimes seizures happen because of:

High fever, which can be associated with an infection such as meningitis

Lack of sleep

Low blood sodium (hyponatremia), which can happen with diuretic therapy

Medications, such as certain pain relievers, antidepressants or smoking cessation therapies, that lower the seizure threshold

Head trauma that causes an area of bleeding in the brain

Stroke

Brain tumor

Illegal or recreational drugs, such as amphetamines or cocaine

Alcohol abuse, during times of withdrawal or extreme intoxication

Complications

Having a seizure at certain times can lead to circumstances that are dangerous for you or others. You might be at risk of:

Falling. If you fall during a seizure, you can injure your head or break a bone.

Drowning. If you have a seizure while swimming or bathing, you're at risk of accidental drowning.

Car accidents. A seizure that causes either loss of awareness or control can be dangerous if you're driving a car or operating other equipment.

Pregnancy complications. Seizures during pregnancy pose dangers to both mother and baby, and certain anti-epileptic medications increase the risk of birth defects. If you have epilepsy and plan to become pregnant, work with your doctor so that he or she can adjust your medications and monitor your pregnancy, as needed.

Emotional health issues. People with seizures are more likely to have psychological problems, such as depression and anxiety. Problems may be a result of difficulties dealing with the condition itself as well as medication side effects.

The epilepsies and seizures: Hope through research. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Epilepsies-and-Seizures-Hope-Through. Accessed May 24, 2017.

A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.org," "Mayo Clinic Healthy Living," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.